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Paul
Asked: 2009-10-29 04:44:29 +0800 CST

GigE ethernet switch backplane bandwidth

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While looking for a 16- or 24-port gigabit ethernet switch with at least 6 VLANs and port mirroring (packet duplication to a monitoring port), I came up with three candidates (there are more): Cisco SRW2024, Netgear GS724T and HP ProCurve 1810G

I need any VLAN to be capable of at least one full GigE-communication between two ports that is not disturbed by any other traffic.

What I can't figure out is: Are these switches capable of switching multiple full-load GigE-links that sum up to 6xGigE? In the past this was known as the backplane capacity (especially when stacking multiple switches to form a giant broadcast domain) but now some don't give any information (HP in the case of the J9450A) and the others state "Nonblocking, store-and-forward switching mechanism" or even "Bandwidth: 48 Gbps".

Is it common knowledge that GigE switches handle anything you send to them as long as no single-link capacity is overloaded?

bandwidth

4 Answers

  1. Many manufacturers claim 48Gbps capacity for such switches, but there may still be significant differences in performance. You also need to compare packets/sec capacity and switching latency (if you can even find those specs in product literature).

    For example, recently I replaced a Netgear JGS524 (24-port gig unmanaged) with a Cisco 2960G-24 in an iSCSI network; and the before-and-after benchmarks (bonnie++ on an iSCSI filesystem) showed 30-40% improvements in throughput and 10-20% improvements in latency.

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  2. Best Answer

    All three of the links you provided specify 48Gbps of throughput/bandwidth/switching-capacity if you read their specs. So yes, you'll be fine for full 1/2Gbps-to-1/2Gbps port-to-port linking with any of them.

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  3. To make it short an simple:

    1. Netgear - I had diverse trouble with those, avoid them

    2. Cisco - great gear no question, but higher pricetag

    3. HP - my recommendation, good performance and easy to configure

    Best regards...

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  4. I went with the HP switch and it works flawlessly. No fan I could hear, meaningful LEDs, plenty of VLANs. But does it switch 48 GiBit/s? Well I don't know. That is because I had to learn that even the "server style" Intel dual-port GigE-cards seem to allow 1 GiBit/s through any of their ports at any given time - both directions combined! Full duplex sending and receiving with 1 GiBit/s each is not possible.

    Since only one cable runs from each PC to the switch and my test had 6 PCs, the best I could see was 3 GiBit/s total through the switch. In fact, I did see 3 GiBit/s so it seems at least the bandwidth is realistic.

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